linux64 on amd64 10.3-STABLE

I'm on FreeBSD 10.3-STABLE #0 r298933M amd64. Since some time ago I started to note the following message during boot process:
Additional ABI support: linuxlink_elf_obj: symbol elf64_linux_shared_page_fini undefined
linker_load_file: Unsupported file type
kldload: an error occurred while loading the module. Please check dmesg(8) for more details.
/etc/rc: WARNING: Unable to load kernel module linux64
I'm not sure, why is that, and what should I do? I've seen that linux64 is on the way, but don't know in what state it is now.

I have linux_enable="YES" in rc.conf. option COMPAT_LINUX32 in custom kernel configuration file.